A/C-Heater Blower Power

[Gluchie]

My 1972 NYB has an electrical issue with the heater / ac switch. There is no power to the switch, but if I find a power source I can get the blower motor to run. I have tried to trace the lines on the harness, but lose it in the dash. Something had burned the switch terminal, so I need to replace the switch as well. I have a NOS switch but have not figured out how to take the old one out. If anyone in S/E Michigan is interested in working on her, please let me know.

 

[cbarge]

Dooes your NYB have the Auto Temp AC? or "normal" AC?

 

[Gluchie]

Normal AC

 

[cbarge]

Normal AC

Good. Auto Temp can be a nightmare.
You can pull wiring diagrams off the WWW or have a Shop Manual handy.
The switch feeds power to the blower resistor which feeds power to the blower motor.

Did you check the fuses?

To test the blower motor,run a jumper wire from the BATT terminal of the fuseblock to the plug for the blower motor. It should run.If the jumper sparks/arc/gets hot the blower is fubarred.
Use a multi-meter to test continuity on the blower resistor and the rest of the AC system wiring.
The HVAC controls do run on vacuum but there is a power wire that feeds it as well.
Check to see if it is burned/shorted.
To do that I recommend pulling the dash faceplate for access.
To do that you need to drop the steering column down enough for it to clear the faceplate.
Electrical is not that complicated--just take your time,stop and think.
I know a lot of people are not comfortable with the electrical in our old Mopars--and I get it.
A lot of shops shy away from it or charge straight time by the hour and that can turn expensive.
Just buy me a plane ticket and I will come fix her up!! LOL

 

[Gluchie]

Thanks for info, I have tested the blower and did replace the resistor. I will try to locate the vacuum power feed.

 

[cbarge]

Thanks for info, I have tested the blower and did replace the resistor. I will try to locate the vacuum power feed.

The single spade is by itself in the middle on the back of the controls is the power feed.
The HVAC controls can fail and was common.
Lots of them still available if it is needed.

 

[Davea Lux]

Be sure to run a test light off both ends of the blower fuse. Bar fuses can look perfect but if the solder on the end caps has failed you can still have an open connection, also check the end clips for the fuse for corrosion as that will also cause an open circuit. From there it is a matter of going down the wiring with a test light to see where there should be power. Contacts that are burned inside the blower switch are also a common failure that disables the blower.

Dave

 

[Gluchie]

Thanks all for the information. I will be checking these options out shortly.